Dual Battery 200 Series

Submitted: Saturday, Jun 30, 2012 at 18:11
ThreadID: 96602 Views:10783 Replies:8 FollowUps:3
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Have just taken delivery of a 200 series which has 2 batteries wired in parralell. I am going to put in larger size batteries and then split them so that I can run the accessories off one of them. I have become confused from too much research and advice from too many vehicle with other vehicles so I am looking for advice from what people and brands/models of isolators they have. If possible I would also like to be topping up the charge in the camper battery when on the run vis the Anderson plug on the back of the vehicle.
For years I have had the old 80 series wired in paralell and then just manually switched it to isolate it. Never had a flat bettery but was thinking of having something more automatic but I read somewhere that the alternator on the 200 doesn't always fully charge the second battery let alone one fitted to the camper.

Thanks in advance.
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Reply By: Ross M - Saturday, Jun 30, 2012 at 19:33

Saturday, Jun 30, 2012 at 19:33
If you separate the batteries and use a solenoid as you have done so before, then I can see no reason why it is any different to having the original setup.
It charged both when constantly locked and now you have two which are locked together by the solenoid.
No electrical difference.

With a heavy cable to the rear and an Anderson plug it should also charge the van battery too. Mine does.

If you find something isn't working as you require it to, eg not enough charge to rear, then and only then will you have to look at alternatives.
AnswerID: 489789

Reply By: Bush Wanderer - Saturday, Jun 30, 2012 at 19:35

Saturday, Jun 30, 2012 at 19:35
I went for a redarc dc to dc charger. Looks after the second battery very well, and ensures that battery is always charged as high as it can go....alternator issue is of no concern with the dc to dc charger. I gave up on bulk chargers more than 4 years ago for this reason.

AnswerID: 489791

Reply By: Dennis Ellery - Saturday, Jun 30, 2012 at 22:11

Saturday, Jun 30, 2012 at 22:11
It’s not the alternator that’s the problem.
With solid state isolators (electronic) the second battery won’t charge as fully as the first battery.
If you use a mechanical isolator like a Redarc both batteries will charge equally.
As for the camper battery use a DC/DC charger to overcome the voltage drop between your alternator and the camper.
AnswerID: 489808

Reply By: Member - Serendipity(WA) - Sunday, Jul 01, 2012 at 01:29

Sunday, Jul 01, 2012 at 01:29
I have heard so this needs to be checked that you should not separate the two batteries as the 200 series needs both to run all the electronics onboard.

As to the 200 series not charging enough this is a known fact and it has to do with meeting pollution control requirements I believe. There is a workaround and you can install an alternator booster diode. You can get them from one of the business members on this site who is pretty good.




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AnswerID: 489818

Reply By: Member - Boobook - Sunday, Jul 01, 2012 at 06:05

Sunday, Jul 01, 2012 at 06:05
Many 200 owners including myself have split the batteries and used something like the Redarc isolator. I recommend the 200A one.

The Pass side will take a N70 battery, get a good one as the starter, the Drivers side will take an N70 or a 31 size if you slightly bend the battery clamp. Mine has been like that for 4 years and is ok. Make sure you have an override button to parallel the batteries, Great for winching and self jump starting.

Toyota sent out a letter specifically advising against putting in a 3rd battery as per how Pirhana and ARB do it. You have to move a lot of scary bleep to fit it in.

Re the charging, it is fine with the alternator, however the diode mentioned above does top it up more, especially if you have a camper. It is a 30 cent diode.
AnswerID: 489823

Reply By: Member - Captain (WA) - Sunday, Jul 01, 2012 at 10:24

Sunday, Jul 01, 2012 at 10:24
Hi Outnabout,

I have split the batteries in my 200 with a Redarc isolator and it has worked fine for over 4 years now. I upgraded my batteries to N70Z size and this is ample for starting. The 70 series TTD V8 only comes with one battery so even Toyota are happy to use one battery to start the V8 when it has the right size one...

The "issue" with the alternator is that it is TEMPERATURE controlled and varies its voltage acording to underbonnet temp. The reson for this is to minimise electrolyte boiling in hot underbonnet conditions with too high a voltage. However, while this is fine for normal use, it does mean an AUX battery will take longer to charge due to the typical 13.3 - 13.6V the batteries receive.

I have had mininimal issue charging my AUX battery, however when it has run down I typically drive for some distance. If only driving short distances, it can be an issue and a dc-dc charger could be advantageous. While one could put in the diode voltag booster, I have not as I believe the lower voltage helps the life of the batteries, especially the starter battery.

As for charging a van battery, even when you have big cables (I have 64mm2 copper wire), the voltage loss is still too high and a dc-dc charger is required to charge a large battery bank - I have 240 a/hr AGMs. I did try just alternator charging but could not get close to a full charge even with 8 hours driving so went down the Redarc BCDC 1240 charger in my van and it works a treat.

Check out www.LCOOL.org for all things about landcruisers (Land Cruiser Owners On Line).


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AnswerID: 489838

Reply By: Sand Man (SA) - Sunday, Jul 01, 2012 at 13:24

Sunday, Jul 01, 2012 at 13:24
I have a slightly different point of view.

Regardless of the 200 series having two batteries in the engine bay, you still need to install heavy duty cabling to supply power to a fridge, which usually would be located in the back of the vehicle, plus the wiring for remote connection/charging of batteries in a towed camper or van.

So why not put your auxiliary battery in the most practical location close to heaviest use, such as a fridge and a circuit to a camper, etc.
With something like the Sidewinder Flyer (a "smart" battery box) mounted in the rear of the storage space and adjacent to where a fridge would be, you would have the best location for an auxiliary battery.
The Flyer takes up to a 130Ah battery (I selected a 100Ah AGM) and with the supplied cabling to connect to the starting battery and a built-in isolator to protect that starting battery, you have a all encompassing solution for $395, plus the battery of your choice. The fridge then plugs directly into the Flyer's merit style 12v outlet. An AGM battery installed in this box is a safe and practical way to contain a battery in the cargo space, without the need for specialised venting.

Now, you can add to this, a "patch lead" accessory made from the same heavy duty cabling and with an Anderson plug on each end to give you a removable connection for a camper or caravan. The patch lead is simply plugged into the 50 amp output Anderson connector on the Flyer and supplies an effective 12 volt supply to remote batteries located in the camper or caravan. An internal fuse protects that circuit from possible shorts, etc. I just place the lead underneath the corner of the tailgate and the weather seal compresses around it, without damaging the cable.
The camper connection is then plugged into the Anderson connector "sticking out the back".

I have ensured a quality supply to the remote batteries in my camper by installing a dc-dc charger (Ctek D250S Dual) close to them. This eliminates any possible voltage drop by providing an optimal voltage of 14.4 volts at 20 amps, to ensure the remote AGM batteries are given a full multi-stage charging regime, with the added ability to connect a solar panel array to the auxiliary port when stationary.

The overall cost of the Flyer solution will be compatible with that of a stand-alone isolator, plus all the cabling and connections required to provide adequate circuits for a fridge and remote connection for a camper.

Sidewinder Flyer


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AnswerID: 489865

Reply By: Member - Phil G (SA) - Sunday, Jul 01, 2012 at 21:05

Sunday, Jul 01, 2012 at 21:05
Gday David,
I'd keep it simple - use wet cell batteries under the bonnet and the suggested (upsized) 200A Redarc solenoid isolator or for a $100 more get the Rotronics MH10.

Sure the alternator is temperature compensated but that is entirely appropriate when the aux battery is also under the bonnet. I wouldn't consider a Redarc DC-DC for your installation because it has no temp compensation and is likely to boil the batteries. A Ctek D250S is temp compensated if you felt the need for a DC-DC charger.

As for the camper battery - if its just for lights and simple stuff, then just charge via the anderson plug. If you have a compressor fridge in the camper then a DC-DC charger is a good idea.

AnswerID: 489911

Follow Up By: Outnabout.. - Sunday, Jul 01, 2012 at 21:34

Sunday, Jul 01, 2012 at 21:34
Thanks Phil,

Simple is what I want. What would be wrong with just having a big isolation manual switch like I have on the 80. Obviously if one forgets to switch it I could get two flat batteries but have never had that before. I like the idea of two batteries wired paralell as that way you are always taking equal power off each and topping up just a little on each. The reality is with most systems the auxillary battery is just sitting there doing nothing most of the time.

The camper battery is solely for lighting and now only runs LED lights and is an N70 so will last a long time.

FollowupID: 765033

Follow Up By: Member - Phil G (SA) - Sunday, Jul 01, 2012 at 21:45

Sunday, Jul 01, 2012 at 21:45
Nothing wrong with a big isolation switch - thats what I installed on Amy's 80series. My only warnings are
#1 use a decent switch - those 100Amp $15 key swtches don't cut it - they burn out from the cranking current. I now prefer the heavier duty compact Blue Seas switches.
#2 if one batteries dies, it will pull the other down with it. A solo traveller might then be stranded, so I usually don't suggest it for solo travellers.
FollowupID: 765035

Follow Up By: Outnabout.. - Sunday, Jul 01, 2012 at 23:01

Sunday, Jul 01, 2012 at 23:01
The switch I used on my 80 was about 400Amp from memory of a tractor so would probably do the same. I usually change batteries every two years to reduce the chance of dud batteries and then put the best to the camper. Can carry a spare for remote trips in the camper as a backup.
FollowupID: 765051

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